Die seal ring structure

ABSTRACT

The invention provides a die seal ring structure. The die seal ring structure includes an inner seal ring portion surrounding an integrated circuit region. An outer seal ring portion is surrounded by a scribe line, surrounding the inner seal ring portion, wherein the outer seal ring portion has an outer top metal layer pattern with a first width extending over the inner seal ring portion and connecting to an inner next-to-top metal layer pattern of the inner seal ring portion. A first redistribution pattern is disposed on the outer top metal layer pattern, having a second width which is narrower than the first width. A second redistribution pattern is disposed on the first redistribution pattern. A redistribution passivation layer covers the second redistribution pattern and the inner seal ring portion, wherein the redistribution passivation layer is separated from the scribe line by a second distance.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/513,117 filed Jul. 29, 2011, the entirety of which is incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a die seal ring structure, and inparticular, to a die seal ring structure having a crack stop functionwithout attachment of a metal layer thereto.

2. Description of the Related Art

A die seal ring is generally formed between scribe lines and a peripheryregion of integrated circuits of each die of a wafer, composed byalternatively laminating dielectric layers and metal layers, whichinterconnect by vias through the dielectric layers. When a wafer dicingprocess is performed along the scribe lines, the die seal ring can blockunintended stress cracks from the scribe lines to the integratedcircuits produced by the wafer dicing process. Also, the die seal ringcan block moisture penetration or chemical damage like acid, alkalinecontaining or diffusion of contaminating species. In the currentsemiconductor technology, a double die seal ring structure has beendeveloped to solve the more significant problem of cracks. However, thetop-most layer has a poor crack stop function due to further scaling ofthe semiconductor device and demand for smaller dimensions and increasedfunctions of consumer products.

Thus, a novel die seal ring structure with a good crack stop function isdesirable.

BRIEF SUMMARY OF INVENTION

A die seal ring structure is provided. An exemplary embodiment of a sealring structure comprises an inner seal ring portion surrounding anintegrated circuit region. An outer seal ring portion is surrounded by ascribe line, surrounding the inner seal ring portion, wherein the outerseal ring portion has an outer top metal layer pattern with a firstwidth extending over the inner seal ring portion and connecting to aninner next-to-top metal layer pattern of the inner seal ring portion. Afirst redistribution pattern is disposed on the outer top metal layerpattern, having a second width which is narrower than the first width. Asecond redistribution pattern is disposed on the first redistributionpattern, wherein the first redistribution pattern has a third widthwhich is the same as that of the first width. A redistributionpassivation layer covers the second redistribution pattern and the innerseal ring portion, wherein the redistribution passivation layer isseparated from the scribe line by a second distance.

Another exemplary embodiment of a die seal ring structure comprises aninner seal ring portion surrounding an integrated circuit region. Anouter seal ring portion is surrounded by a scribe line, surrounding theinner seal ring portion, wherein the outer seal ring portion has anouter top metal layer pattern. A first redistribution pattern isdisposed on the outer top metal layer pattern. A second redistributionpattern is disposed on the first redistribution pattern on the firstredistribution pattern, wherein the outer top metal layer pattern, andthe first and second redistribution patterns overlap with both the innerand outer seal ring portions. A redistribution passivation layer coversthe second redistribution pattern and the inner seal ring portion,wherein all of the outer top metal layer pattern, and the first andsecond redistribution patterns and the redistribution passivation layerare separated from the scribe line.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 is a cross section of one exemplary embodiment of a die seal ringstructure 500 of the invention.

DETAILED DESCRIPTION OF INVENTION

The following description is a mode for carrying out the invention. Thisdescription is made for the purpose of illustrating the generalprinciples of the invention and should not be taken in a limiting sense.The scope of the invention is best determined by reference to theappended claims. Wherever possible, the same reference numbers are usedin the drawings and the descriptions to refer the same or like parts.

The present invention will be described with respect to particularembodiments and with reference to certain drawings, but the invention isnot limited thereto and is only limited by the claims. The drawingsdescribed are only schematic and are non-limiting. In the drawings, thesize of some of the elements may be exaggerated and not drawn to scalefor illustrative purposes. The dimensions and the relative dimensions donot correspond to actual dimensions to practice the invention.

FIG. 1 is a cross section of one exemplary embodiment of a die seal ringstructure 500 of the invention. As shown in FIG. 1, the die seal ringstructure 500 is positioned between an integrated circuit region 502 anda scribe line 504 of a semiconductor substrate 100. The die seal ringstructure 500 comprises an inner seal ring portion 200 and an outer sealring portion 202. The inner seal ring portion 200 surrounds theintegrated circuit region 502, and the outer seal ring portion 202surrounds the inner seal ring portion 200. Also, the outer seal ringportion 202 is surrounded by the scribe line 504. In this embodiment,the semiconductor substrate 100 may be a p-type semiconductor substrate.The inner seal ring portion 200 and the outer seal ring portion 202 havep+ diffusion regions 206 on a top of the semiconductor substrate 100,respectively. The inner seal ring portion 200 and the outer seal ringportion 202 both comprise a plurality of dielectric layers 208, 308,310, 312, 314 and 316 laminated vertically. The dielectric layers 208,308, 310, 312, 314 and 316 are respectively covered by metal layerpatterns M1, M2, M3, M4, M5 and M6, from bottom to top. The metal layerpatterns M1, M2, M3, M4, M5 and M6 are designed as close-loop patterns.The number of the metal layer patterns is defined by the costumer designfor the integrated circuit region 502 and the scope of the invention isnot limited. In the inner seal ring portion 200, the metal layer patternM1 is coupled to the p+ diffusion regions 206 a by vias 210 through thedielectric layer 208 between the metal layer pattern M1 and the p+diffusion regions 206. The metal layer pattern M2 is coupled to themetal layer pattern M1 by vias 212 through the dielectric layer 308between the metal layer pattern M1 and the metal layer pattern M2. Themetal layer pattern M3 is coupled to the metal layer pattern M2 by vias214 through the dielectric layer 310 between the metal layer pattern M2and the metal layer pattern M3. The metal layer pattern M4 is coupled tothe metal layer pattern M3 by vias 216 through the dielectric layer 312between the metal layer pattern M3 and the metal layer pattern M4. Themetal layer pattern M5 is coupled to the metal layer pattern M4 by vias218 through the dielectric layer 314 between the metal layer pattern M4and the metal layer pattern M5. The metal layer pattern M6 is coupled tothe metal layer pattern M5 by vias 220 through the dielectric layer 316between the metal layer pattern M5 and the metal layer pattern M6. Themetal layer pattern M6 is also referred to as a top metal layer patternM6. The metal layer pattern M5 is also referred to as a next-to-topmetal layer pattern M5, and so on. It is noted that the inner seal ringportion 200 and the outer seal ring portion 202 have a similarlystructure except for the top metal layer pattern M6. The metal layerpatterns M1, M2, M3, M4, and M5 of the inner seal ring portion 200 arerespectively isolated from the widths of the outer seal ring portion 202by a distance S1. Also, the top metal layer pattern M6 of the outer sealring portion 202 is designed to shift toward the inner seal ring portion200, extruding through the gap 222 between the inner seal ring portion200 and the outer seal ring portion 202. That is to say, the top metallayer pattern M6 of the outer seal ring portion 202 extends over theinner seal ring portion 200 and connects to the next-to-top metal layerpattern M5 of the inner seal ring portion 200 through the via 220. Thetop metal layer pattern M6 of the outer seal ring portion 202 isseparated from the scribe line 504 by a distance d3. The top metal layerpattern M6 of the inner seal ring portion 200 has a width W1, which isdesigned to be narrower than a width W2 of the top metal layer patternM6 of the outer seal ring portion 202. Also, the distance S1 is largerthan the distance S2 between the top metal layer pattern M6 of the innerseal ring portion 200 and the top metal layer pattern M6 of the outerseal ring portion 202.

A passivation layer 226 is formed covering the inner top metal layerpattern 200 and the outer top metal layer pattern 202. The firstredistribution pattern 224 is formed through the passivation layer 226by a photolithography and deposition process. As shown in FIG. 1, thefirst redistribution pattern 224 is formed on the outer top metal layerpattern 202. In this embodiment, the first redistribution pattern 224 isalso referred to as a TerMinal Via for Redistribution Layer (TMV_RDL)pattern 224. A second redistribution pattern 228 is formed on the firstredistribution pattern on the first redistribution pattern 224 by aplating process. In this embodiment, the second redistribution pattern228 is also referred to as an aluminum (Al) redistribution layer(AL_RDL) pattern 228. In this embodiment, the second redistributionpattern 228 and pads (not shown) are formed by patterning the same layerformed of aluminum (Al). The AL_RDL pattern 228 electrically connects tothe top metal layer pattern M6 of the outer seal ring portion 202through the TMV_RDL pattern 224. In one embodiment, the TMV_RDL pattern224 has a width W3 smaller than the width W2 of the top metal layerpattern M6 of the outer seal ring portion 202 but larger than the widthW1 of the top metal layer pattern M6 of the inner seal ring portion 200.In one embodiment, the AL_RDL pattern 228 has a width W4 the same as thewidth W2 of the top metal layer pattern M6 of the outer seal ringportion 202. Also, the TMV_RDL pattern 224 is disposed centrally of thetop metal layer pattern M6 of the outer seal ring portion 202.Therefore, edges of the top metal layer pattern M6 of the outer sealring portion 202 is recessed from edges of the top metal layer patternM6 of the outer seal ring portion 202 adjacent thereto. That is to say,the edge of the TMV_RDL pattern 224 to the edge of the top metal layerpattern M6 of the outer seal ring portion 202 is adjacent thereto by adistance d2. In one embodiment, edges 232 of the AL_RDL pattern 228adjacent to the scribe line 504 is aligned to that of the top metallayer pattern M6 of the outer seal ring portion 202. That is to say, theouter top metal layer pattern M6 fully overlaps with the AL_RDL pattern228. Further, the AL_RDL pattern 228 is separated from the scribe line504 by a distance d4 which is the same as that of the distance d3, andthe TMV_RDL pattern 224 is separated from the scribe line 504 by adistance d5 larger than the distances d3 and d4.

Still refer to FIG. 1, a redistribution passivation layer 230 is formedcovering the AL_RDL pattern 228 and the inner seal ring portion 200. Itis noted that the redistribution passivation layer 230 also wrapsvertical edges 232 of the redistribution passivation layer 230. Thepassivation layer 226 and the redistribution passivation layer 230overlap with both the inner and outer seal ring portions 200 and 202. Asshown in FIG. 1, the top metal layer pattern M6 of the outer seal ringportion 202, the TMV_RDL pattern 224, the AL_RDL pattern 228 and theredistribution passivation layer 230 are designed separated from thescribe line 504, thereby allowing a gap 234 which is disposed toseparate the redistribution passivation layer 230 from the scribe line504. In one embodiment, the gap 234 has a width d1 (also referred to asa distance d1 between the redistribution passivation layer 230 and thescribe line 504), and a portion of the passivation layer 226 is exposedto the gap 234. In one embodiment, the width d1 is designed smaller thanthe distance d3 between the scribe line 504 and the top metal layerpattern M6 of the outer seal ring portion 202, the distance d4 betweenthe scribe line 504 and the AL_RDL pattern 228 and the distance d5between the scribe line 504 and the TMV_RDL pattern 224. Afterperforming the aforementioned process, one exemplary embodiment of a dieseal ring structure 500 of the invention is completely formed.

One exemplary embodiment of a die seal ring structure 500 of theinvention has the following advantages. The top metal layer pattern M6of the outer seal ring portion 202, the first redistribution pattern224, the second redistribution pattern 232 and the redistributionpassivation layer 230 are designed to shift toward the inner seal ringportion 200, allowing a gap 234 to be disposed to separate theredistribution passivation layer 230 from the scribe line 504 withoutexposing any metal layers. The gap 234 can provide a crack stop functionfor the die seal ring structure 500 during the wafer dicing process. Thedie seal ring structure 500 with the gap 234 can avoid attacking? themetal layer patterns (including redistribution layer patterns and metallayer patterns of the inner and outer seal ring portions) during thesubsequence pad cleaning process using the acid based salvation. Also,the gap 234 is designed to provide enough guard band (enough largedistance d6 between a bottom of the gap 234 and the underlying metallayer pattern M5 of the outer seal ring portion 202) for over-etching ofthe pad cleaning process, if it happens.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

1. A die seal ring structure, comprising: an inner seal ring portionsurrounding an integrated circuit region; an outer seal ring portionsurrounded by a scribe line, surrounding the inner seal ring portion,wherein the outer seal ring portion has an outer top metal layer patternwith a first width extending over the inner seal ring portion andconnecting to an inner next-to-top metal layer pattern of the inner sealring portion; a first redistribution pattern on the outer top metallayer pattern, having a second width which is narrower than the firstwidth; a second redistribution pattern on the first redistributionpattern; and a redistribution passivation layer covering the secondredistribution pattern and the inner seal ring portion, wherein theredistribution passivation layer is separated from the scribe line by asecond distance.
 2. The die seal ring structure as claimed in claim 1,wherein the second redistribution pattern has a third width which is thesame as that of the first width.
 3. The die seal ring structure asclaimed in claim 1, wherein the inner seal ring portion has an inner topmetal layer pattern having a fourth width which is narrower than thefirst width.
 4. The die seal ring structure as claimed in claim 3,further comprising a passivation layer covering the inner top metallayer pattern and the outer top metal layer pattern, wherein the firstredistribution pattern is formed through the passivation layer.
 5. Thedie seal ring structure as claimed in claim 1, wherein an edge of thefirst redistribution pattern to an edge of the outer top metal layerpattern adjacent thereto is separated by a second distance.
 6. The dieseal ring structure as claimed in claim 1, wherein the outer top metallayer pattern is separated from the scribe line by a third distance. 7.The die seal ring structure as claimed in claim 6, wherein the firstdistance is smaller than third distance.
 8. The die seal ring structureas claimed in claim 1, wherein an edge of the second redistributionpattern adjacent to the scribe line is aligned to an edge of the outertop metal layer pattern adjacent to the scribe line.
 9. The die sealring structure as claimed in claim 3, wherein a portion of thepassivation layer is exposed from the redistribution passivation layer.10. The die seal ring structure as claimed in claim 1, wherein the firstand second redistribution patterns overlap with both the inner and outerseal ring portions.
 11. The die seal ring structure as claimed in claim3, wherein the outer top metal layer pattern and the inner top metallayer pattern are at the same level, and the outer top metal layerpattern is separated from the inner top metal layer pattern by a fourthdistance.
 12. The die seal ring structure as claimed in claim 11,wherein the outer seal ring portion has an outer next-to-top metal layerpattern separated from the inner next-to-top metal layer pattern by afifth distance larger than the fourth distance.
 13. A die seal ringstructure, comprising: an inner seal ring portion surrounding anintegrated circuit region; an outer seal ring portion surrounded by ascribe line, surrounding the inner seal ring portion, wherein the outerseal ring portion has an outer top metal layer pattern; a firstredistribution pattern on the outer top metal layer pattern; a secondredistribution pattern on the first redistribution pattern, wherein theouter top metal layer pattern, and the first and second redistributionpatterns overlap with both the inner and outer seal ring portions; and aredistribution passivation layer covering the second redistributionpattern and the inner seal ring portion, wherein all of the outer topmetal layer pattern, and the first and second redistribution patternsand the redistribution passivation layer are separated from the scribeline.
 14. The die seal ring structure as claimed in claim 13, whereinthe outer top metal layer pattern fully overlaps with the secondredistribution pattern.
 15. The die seal ring structure as claimed inclaim 13, wherein a width of the first redistribution pattern isnarrower than the widths of the outer top metal layer pattern and thesecond redistribution pattern.
 16. The die seal ring structure asclaimed in claim 13, wherein the first redistribution pattern is fullycovered by the second redistribution pattern.
 17. The die seal ringstructure as claimed in claim 13, wherein the redistribution passivationlayer is separated from the scribe line by a gap having a width, and thewidth is smaller than a first distance between the outer top metal layerpattern and the scribe line.
 18. The die seal ring structure as claimedin claim 17, wherein a second distance between the first redistributionpattern and the scribe line is smaller than the first distance.
 19. Thedie seal ring structure as claimed in claim 17, wherein the secondredistribution pattern is separated from the scribe line by a thirddistance, wherein the third distance is the same as the first distance.20. The die seal ring structure as claimed in claim 13, wherein theouter top metal layer pattern and the second redistribution pattern havethe same width.
 21. The die seal ring structure as claimed in claim 13,wherein the inner seal ring portion has an inner top metal layer patternwith a width which is narrower than the outer top metal layer pattern.22. The die seal ring structure as claimed in claim 19, furthercomprising a passivation layer covering the inner top metal layerpattern and the outer top metal layer pattern, wherein the firstredistribution pattern is formed through the passivation layer.